Note: Descriptions are shown in the official language in which they were submitted.
2I~5154
6-51,757 comb.
METHOD AND APPARATUS FOR PROCESSING EXHAUST GAS
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a method and an
apparatus for processing an exhaust gas discharged from
an internal combustion engine such as a diesel engine,
in which fine particles i.e. soots trapped in a filter
are removed outside of the filter so as to regenerate
the filter and the removed fine particles are trans-
ported outside of an exhaust system and processed.
Related Art Statement
An exhaust gas discharged from a diesel engine
includes a large number of fine particles mainly made of
carbon, and thus this is a cause of a public nuisance
generation. Therefore, various methods for trapping or
eliminating such a fine particles in an exhaust gas are
disclosed.
For example, Japanese Patent Laid-Open Publica-
tion No. 1-159408 (JP-A-1-159408) discloses a method of
removing fine particles trapped in a filter by using an
intermittent counter flow and firing the removed fine
particles in a re-trapping portion arranged in an
exhaust gas passage near the filter. Moreover, Japanese
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Patent Application No. 5-198409 discloses a method of
removing fine particles by using two kinds of counter
flows, transporting the removed fine particles to a
place remote from the filter and outside of the exhaust
05 gas passage by the counter flow mentioned above, and
firing the removed and transported fine particles.
However, in the method disclosed in JP-A-l-
159408, since the re-trapping portion is arranged under
the filter or in the exhaust gas passage near the
o filter, there is a possibility that the fine particles
once removed by using the counter flow are returned to
the filter by an exhaust gas.
Moreover, in the method disclosed in Japanese
Patent Application No. 5-198409, since it is necessary
15 to use two kinds of the counter flows, the apparatus for
performing the method mentioned above is complicated.
Further, since it is necessary to transport the removed
fine particles to the place remote from the filter by
using the counter flow, a large amount of the counter
20 flow must be used. If the method mentioned above is
used for an apparatus of processing an exhaust gas from
an engine, it is preferred that an air supply source
used for an exhaust brake system and so on of vehicles
is also used for a counter air supply source from the
' 25 vie~points of cost, dimensions and so on. In this
case, if a large amount of the counter air is used, it
- 21 q51 $~
is necessary to make an actuator of the exhaust brake
system large, and this causes a bad operation of the
actuator.
Summary of the Invention
05 It is an object of the present invention to
eliminate the drawbacks mentioned above and to provide a
method and an apparatus for processing an exhaust gas,
in which, if fine particles are removed from a filter,
transported by a counter flow and processed, the removed
o fine particles are not returned to the filter.
It is an another object of the present invention
to provide a method and an apparatus for processing an
exhaust gas, in which the fine particles can be removed,
transported and processed effectively even by a small
15 amount of the counter air.
It is an another object of the present invention
to provide a method and an apparatus for processing an
exhaust gas, in which the fine particles can be removed,
transported and processed effectively by an apparatus
20 having an simple constitution.
According to the invention, a method for
processing an exhaust gas discharged from an internal
combustion engine, in which fine particles trapped in a
filter main body of a filter are removed by flowing an
25 intermittent counter air, whose flowing direction is
reversed to an exhaust gas flowing direction, through
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said filter main body, and the removed fine particles
are transported outside of an exhaust gas system and are
processed, comprises a first step in which an exhaust
gas flow is stopped, and said counter air is supplied
os intermittently form a counter air discharge valve
through a counter air supply pipe into a first counter
room arranged at a downstream position of said filter
main body; a second step in which fine particles trapped
in said filter main body are removed by said counter air
o flowing through said filter main body; a third step in
which said removed fine particles are transported to a
second counter room arranged at an upstream position of
said filter main body by said counter flow, and said
transported fine particles are further transported to a
5 process portion arranged at said second room and isolated
from said exhaust gas flow; and a fourth step in which
said transported fine particles are fired in said
process portion.
Moreover, according to the invention, an
20 apparatus for processing an exhaust gas discharged from
an internal combustion engine, in which fine particles
trapped in a filter main body of a filter are removed by
flowing an intermittent counter air, whose flowing
direction is reversed to an exhaust gas flowing
25 direction, through said filter main body, and the
removed fine particles are transported outside of an
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exhaust gas system and are processed, comprises a filter
having a first counter room arranged at a downstream
position of said filter main body and a second counter
room arranged at an upstream position of said filter
05 main body; an exhaust gas supply pipe for supplying said
exhaust gas to said filter; an exhaust gas discharge
pipe communicated from said first counter room to an
outside; a process portion arranged at said second room
and isolated from said exhaust gas flow, in which said
o removed fine particles are fired; a transport pipe, one
end of which is connected to said second counter room
and the other end of which is connected to said process
portion; a counter air supply means for for supplying a
counter air, whose flowing direction is reversed to said
15 exhaust gas flowing direction, to said counter room; an
exhaust gas supply valve arranged in said exhaust gas
supply pipe; and an exhaust gas discharge valve arranged
in said exhaust gas discharging pipe.
Brief Description of the Drawinqs
Fig. 1 is a schematic view showing a first
embodiment of an exhaust gas processing apparatus
according to a present invention;
Fig. 2 is a schematic view illustrating a main
portion of the first embodiment in the case of a fine
25 particle trapping operation according to the invention;
Fig. 3 is a schematic view depicting a main
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portion of the first embodiment in the case of a filter
regenerating operation according to the invention;
Fig. 4 is a perspective view showing one
embodiment of a filter main body according to the first
05 embodiment of the invention;
Fig. 5 is a cross sectional view illustrating
one embodiment of the filter main body shown in Fig. 4;
Fig. 6 is a cross sectional view depicting one
embodiment of the filter main body in the case of the
o filter regenerating operation according to the
invention;
Fig. 7 is a schematic view showing a filter of
the first embodiment according to the invention;
Fig. 8 is a graph illustrating a relation in a
15 first counter room between pressure variation and time
according to the first embodiment of the invention;
Fig. 9 is a timing chart depicting operations of
exhaust gas supply valves and a counter air discharge
valve according to the first embodiment of the
20 invention;
Fig. 10 is a cross sectional view showing one
embodiment of a process portion according to the first
embodiment of the invention;
Fig. 11 is a schematic view illustrating another
25 embodiment of the exhaust gas processing apparatus
according to the invention in which one filter is used;
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Fig. 12 is a cross sectional view depicting a
filter according to a second embodiment of the invention;
Fig. 13 is a timing chart showing a relation
between a pressure difference defined by pressures at an
05 inlet portion and an outlet portion of the filter main
body according to the second embodiment of the invention;
Fig. 14 is a schematic view illustrating a third
embodiment of the exhaust gas processing apparatus
according to the invention;
oFig. 15 is a schematic view depicting a main
portion of the third embodiment in the case of the fine
particle trapping operation according to the invention;
Fig. 16 is a schematic view showing a main
portion of the third embodiment in the case of the
15 filter regenerating operation according to the invention;
Fig. 17 is a schematic view illustrating a
fourth embodiment of the exhaust gas processing
apparatus according to the invention;
Fig. 18 is a schematic view depicting a main
20 portion of the fourth embodiment in the case of the fine
particle trapping operation according to the invention;
and
Fig. l9 is a schematic view showing a main
portion of the fourth embodiment in the case of the
25 filter regenerating operation according to the
invention .
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Description of the Preferred Embodiment
Hereinafter, the present invention will be
explained in detail with reference to the drawings.
(First Embodiment)
05 Figs. 1 to 10 are schematic views respectively
showing the first embodiment of the invention. As shown
in Fig. 1, an apparatus for processing an exhaust gas
according to the first embodiment of the invention
comprises (1) filters 2, 4, (2) counter air supply
o portion 3, (3) exhaust gas supply pipe 7, (4) exhaust
gas discharge pipe 8, (5) transport pipe 5, (6) process
portion 6.
(1) Filter
As shown in Fig. 1, an exhaust gas discharged
15 from a diesel engine can be flowed through one of or
both of a first filter 2 and a second filter 4. In this
embodiment, if the first filter 2 and the second filter
4 are alternately regenerated, an exhaust gas processing
operation can be continuously performed.
Fig. 7 is a schematic view showing a construc-
tion of the filter 2 or 4. As shown in Fig. 7, a filter
main body 20 is accommodated in a container 201 having a
cylindrical shape. A first counter room 210 is formed
at a downstream position of the filter main body 20, and
25 a second counter room 212 is formed at an upstream
position of the filter main body 20.
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The filter main body 20 is made of a porous
honeycomb structural body having a cylindrical shape,
which is formed integrally by extruding a cordierite
batch. As shown in Figs. 4 and 5, a number of through
os holes 30 arranged parallel to an axis of the filter main
body 20 are formed. The through holes 30 have such a
construction that partition walls 34 extended in x
direction and partition walls 36 extended in y direction
are crossed with each other and the crossed partition
walls 34 and 36 are extended in z direction, as shown in
Fig. 4. One er.d of the through hole 30 is sealed by a
plug member 38, and the other end of the adjacent through
hole 30 is sealed by a plug member 39. In this case, as
shown in Fig. 4, the through holes 30 arranged at both
5 ends of the filter main body 20 are sealed by the plug
members 38 and 39 like a checker flag pattern. There-
fore, as shown in Fig. 5, an exhaust gas is supplied
from the through holes 30, at which the plug members 39
are arranged, into the filter main body 20. Then, the
20 supplied exhaust gas is passed through the partition
walls 36 as shown by an arrow in Fig. 5. Then, the
passed through exhaust gas is discharged from the adjacent
through holes 30. In this case, fine particles in the
exhaust gas are trapped by the partition walls 36 at its
25 exhaust gas supply side. The trapped fine particles are
piled up gradually corresponding to a lapse of time.
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As shown in Fig. 7, the filter main body 20 is
secured to an inner wall 201a of the cylindrical
container 201 by seal rings 202, 203 and support rings
204,205. A space 206 is formed between the filter main
05 body 20 and the inner wall 201a of the container 201.
A filter support member 207 is arranged in the space
206. As for the filter support member 207, use is made
of a ceramic mat used for supporting a catalyst carrier
of an exhaust gas purifying converter assembled in a
gasoline engine vehicle. The filter support member 207
flJnctions to not only support but also cushion the
filter main body 20. In this embodiment, as for the
filter support member use may be made of a combination
of the ceramic mat and a stainless wire mesh mat.
The seal rings 202, 203 have a circular shape.
In order to airtightly seal a boundary between a
circumferential peripheral portion of an exhaust gas
inlet end or an exhaust gas outlet end of the filter
main body 20 and the inner wall 201a of the container
20 201, a gasket not shown is arranged between the seal
ring 202 or 203 and the filter main body 20.
The support rings 204, 205 have also a circular shape.
The support rings 204, 205 are secured to the inner wall
201a of the container 201 by a bolt not shown in such a
25 manner that the filter main body 20 is compressed in a
through hole direction by the support rings 204 and 205.
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The first counter room 210 is formed in the
container 201 at an exhaust gas downstream position of
the filter main body 20. A counter air supply inlet 211
is communicated to an inner wall 210a of the first
05 counter room 210. The second counter room 212 is formed
in the container 201 at an upstream position of the
filter main body 20. An exhaust gas supply inlet 213
and a transport inlet 214 are communicated to an inner
wall 212a of the second counter room 212. The transport
o inlet 214 is arranged downward from the exhaust gas
supply inlet 213.
In the embodiment mentioned above, since the
filter main body 20 is secured to the inner wall 201a of
the container 201 with the space, the filter main body
20 is not moved gradually if a vibration due to the
engine or a vibration during a movement of the vehicle
is applied thereto, and thus it is possible to prevent a
crack generation and a breakage of the filter main body
20. Moreover, the filter main body 20 is made of the
20 honeycomb structural body, and thus it endures a
relatively high compression strength in a through hole
direction. Therefore, if the support rings 204, 205 are
secured to the inner wall 201a of the container 201 by a
bolt and so on in such a manner that the filter main
25 body 20 is compressed in a through hole direction by the
support rings 204 and 205, it is also possible to support
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the filter main body 20 without generating a crack and a
breakage.
Further, since a boundary between a circumfer-
ential peripheral portion of an exhaust gas inlet end or
os an exhaust gas outlet end of the filter main body 20 and
the inner wall 201a of the container 201 is sealed, all
the exhaust gas can be passed through the filter main
body 20. Moreover, in this case, since the exhaust gas
is not directly supplied to the filter support member
207, it is possible to prevent a deterioration of the
f ilter support member 207. Furthermore, since the
filter main body 20 is partly supported by a pressure
applied to the above sealed portion, it is possible to
decrease a support pressure of the filter main body 20,
15 and thus it is possible to prevent a breakage of the
filter main body 20.
It should be noted that a cross section of the
filter is generally circular, but it is possible to use
the filter having a square, a rectangular, an ellipse,
20 or the other cross section. Moreover, a shape of the
through hole is generally square, but it is possible to
use the through hole having a circular, a triangular, or
a hexagonal shape.
As the materials for the filter, it is preferred
25 to use a porous cordierite from the view point of a
thermal shock resistivity, an endurability, a gas seal
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performance and a fine particle trapping performance,
and to form the filter by an integral extrusion.
However, it is possible to use a porous ceramic material
such as cordierite, alumina, mullite, silicon carbide,
05 silicon nitride, zirconia, or a three-dimensional net
structural body made of a fired porous metal, a ceramic
fiber or a fiber material such as a metal fiber and so on.
Moreover, since the filter is porous, it
functions to be a muffler. Therefore, it is possible to
o further decrease an exhaust noise if used together with
a usual muffler. As a comparison, the exhaust noises in
the case that only the usual muffler was used and in the
case that the filter was used together with the usual
muffler were detected by a noise meter set beyond a tail
15 pipe. As a result, if use is made of the filter
together with the usual muffler, it is possible to
decrease the exhaust noise by about 5 dB.
(2) Counter air supply portion
As shown in Fig. 1, the counter air supply
20 portion 3 is arranged at an exhaust gas downstream
position of the filter 2 or 4 i.e. at a side of the plug
member 38 of the filter 2 or 4. The counter air portion
3 comprises counter air supply portions 3 and counter
air discharge valves 304 and 305. For example, as the
25 counter air discharge valves 304 and 305, use is made of
a magnetic valve which can perform an open or an close
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operation in a short time. As shown in Fig. 7, one end
of the counter air supply pipe 303 is communicated with
the first counter room 210 of the filter 2 or 4 at the
counter air supply inlet 211. The counter air supply
os inlet 211 has no valve, and thus it has a sufficient
open area.
In Fig. 7, an axis (a) of a counter air flowing
direction in the counter air supply pipe 303 is not
parallel to an axis (b) of the through hole in the
o filter main body 20. In this case, the axis (a) is
crossed orthogonally with respect to the axis (b).
However, in this invention, it is possible to incline
the axis (a) with respect to the axis (b).
Moreover, the other end of the counter air
15 supply pipe 303 is communicated with a counter air tank,
and the counter air tank is communicated with a counter
air supply source. As the counter air supply source, it
is preferred to use a compressor used for an exhaust gas
brake system of the vehicle from the view points of a
20 vehicle carrying performance, and a cost.
Further, in order to minimize an amount of the
counter air to be used, it is necessary to set properly
an amount of the counter air tank, a dimension of the
pipe from the counter air tank to the counter air
25 discharge valve, an opening diameter of the counter air
discharge valve, a flow coefficient, a dimension of the
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pipe from the counter air discharge valve to the first
counter room, an amount of the first counter room or the
second counter room, a dimension of the filter, a shape
of the filter, and so on.
05 If the counter air discharge valves 304, 305 are
opened, the compressed counter air is flowed into the
first counter room 210 through the counter air supply
pipe 303. Therefore, an air pressure of the first
counter room 210 is rapidly increased. Then, as shown
o in Fig. 6 by arrows, the counter air is supplied from
the through ~ole 30~ passed through the partition wall
36, and discharged from the adjacent through hole 30.
Thereby, the fine particles filed up in the through hole
30 are discharged into the second counter room 212.
Since the counter air supply inlet 211 has a
sufficient opening area, a large amount of the counter
air can be supplied in the first counter room in a short
time. Therefore, a large shock can be applied to the
through holes 30 of the filter main body 20. Moreover,
20 since the axis (a) of the counter air flowing direction
in the counter air supply pipe 303 is not parallel to
the axis (b) of the through hole in the filter main body
20, a rapid pressure increase due to the counter air
supplied in the first counter room 210 can be uniformly
25 applied to a surface at an exhaust gas supply side of
the filter main body 20. That is to say, it is possible
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to prevent a local counter air flow, and thus the fine
particles can be uniformly removed from the partition
wall of the filter main body 20, and the removed fine
particles can be transported into the second counter
05 room 212.
In the present invention, it is possible to
project one end of the counter air supply pipe in the
first counter room. Moreover, it is preferred to
decrease a pressure loss in the case that the counter
air is supplied into the first counter room by arranging
a wider taper portion at the end of the counter air
supply pipe in the first counter room.
(3) Exhaust gas supply pipe
One end of the exhaust gas supply pipe 7 is
15 communicated with a diesel engine so as to introduce an
exhaust gas, and the other end of the exhaust gas supply
pipe 7 is communicated with the exhaust gas supply inlet
213 arranged at the inner wall 212a of the second
counter room 212 in the filter 2 or 4. Exhaust supply
20 valves 71 and 72 are arranged in the exhaust gas supply
pipe 7 at a position near the filter 2 or 4.
During the filter regenerating operation by the
counter air, if the exhaust gas supply valves 71, 72 are
closed and the counter air is supplied, the fine particles
25 removed from the filter 2 or 4 are not returned into the
exhaust gas supply pipe 7 by the counter air. Moreover,
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the fine particles in the exhaust gas are not introduced
into the filter 2 or 4.
(4) Exhaust gas discharge pipe
One end of the exhaust gas discharge pipe 8 is
05 communicated with the first counter room 210 of the
filter 2 or 4, and the other end of the exhaust gas
discharge pipe 8 is communicated with the muffler.
Exhaust gas discharge valves 81 and 82 are respectively
arranged in the exhaust gas discharge pipes 8 at a
position near the filter main room 20. The exhaust gas
after the fine particle trapping operation is discharged
from the exhaust gas discharge pipe 8 to the muffler.
During the filter regenerating operation by the
counter air, if the exhaust gas discharge valves 81 and
15 82 are closed and the counter air is supplied, a
pressure in the first counter room is increased rapidly,
and thus the fine particles can be removed sufficiently.
Moreover, the removed fine particles can be effectively
transported into the second counter room 212.
20 ( 5) Transport pipe
One end of the transport pipe 5 is communicated
with a transport inlet 214 arranged at the inner wall
212a of the first counter room 212 in the filter 2 or 4,
and the other end of the transport pipe 5 is communicated
25 with the process portion 6. The transport inlet 214 is
arranged downward with respect to the exhaust gas supply
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inlet 213. Particle discharge valves 51 and 52 are
respectively arranged in the transport valve 5 at a
position near the transport inlet 214.
If the particle discharge valves 51 and 52 are
05 opened, the removed particles in the second counter room
212 can be transported into the process portion 6
through the transport inlet 214 and the the transport
pipe 5 by gravity.
(6) Process portion
o The process portion 6 is arranged under the
filter 2 or 4 i.e. at a position outside of the exhaust
gas system. In the process portion 6, the fine particles
removed from the filter main body 20 and transported
through the transport pipe 5 are fired. In this case,
15 if a distance from an exhaust gas supply end of the
filter main body 20 to the process portion is long, it
is necessary to use a larger counter air supply
apparatus, and thus a vehicle carrying performance
becomes worse. At the same time, it is necessary to use
20 a large amount of the counter air for transporting the
fine particles. It is preferred to set the distance
mentioned above to less than 100 cm, preferably to less
than 70 cm, more preferably to less than 40 cm.
As shown in Fig. 10, the process portion 6
25 comprises a process container 61, a plate 62 arranged at
a bottom of the process container 61, and a discharge
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outlet 60. The fine particles transported to the
process portion 6 through the transport pipe 5 are
fallen down to the plate 62 by gravity. The plate 62 is
a stainless plate having a thickness of 0.5-2 mm.
os An electric heater 50 is arranged under the plate 62.
As the heater 50, use is made of a resistance heating
wire of 200 W, which is wound like a spiral under the
plate 62. The plate 62 is heated by the heater 50, and
the fine particles piled up on the plate 62 are fired.
o After that, a residual ash component is discharged from
the discharge outlet 60.
In the first embodiment mentioned above, as
shown in Fig. 1, the one process portion is used for
both of the first filter and the second filter, but it
15 iS possible to arrange the process portions for the
first filter and the second filter respectively.
In the present invention, the electric heater is
arranged under the plate, but it is possible to arrange
the electric heater in the plate. Moreover, as a fine
20 particle firing means, use is made of a sheath heater or
a glow plug in which the fine particles are fired around
it, or a burner for firing the fine particle directly.
Further, it is possible to improve a firing performance
of the fine particles by using an oxidizing catalyst or
25 a microwave generator together with the firing means
mentioned above. In this case, the firing improvement
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means is arranged at a position near the second counter
room as compared with the firing means. Moreover, a
filter through which an air is transmitted may be
arranged at a part of the process container. In this
05 case, an oxygen component necessary for firing can be
introduced through the filter.
Moreover, as the plate, use may be made of a
ceramic plate. In this case, it is possible to use a
far infrared effect of the ceramic plate.
Hereinafter, valve changeover operations in a
trapping mode and in a counter air processing mode and
an ON/OFF operation of the counter air will be explained
with reference to Figs. 1, 2, 3, 8, and 9.
In the trapping mode, as shown in Fig. 1, the
15 exhaust gas discharge valves 81 and 82 and the exhaust
gas supply valves 71 and 72 are opened, and the particle
discharge valves 51 and 52 are closed. In this case,
the fine particles in the exhaust gas from the diesel
engine are trapped by the filter 2 or 4.
Then, in the counter air processing mode, the
filter main body 20 is processed by the counter air
periodically. This counter air processing process
comprises (A) regenerating process, (B) transporting
process, and (C) processing process.
25 (A) Regenerating process
In the regenerating process, as shown in Fig. 9,
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the exhaust gas discharge valve 81 and the exhaust gas
supply valve 71 are changed to a close state , and just
after this change the particle discharge valve 51 is
changed to an open state. This state is maintained for
05 e.g. 1 second. After e.g. 0.7 second from the particle
discharge vale 51 being changed to the open state, the
counter air discharge valve 304 is opened for e.g. 0.1
second. Thereby, the counter air is introduced into the
first counter room 210.
o In this case, it is preferred to set a relation
between a valve opening duration (t) of the counter air
discharge valves 304, 305 and a duration (T) to T/tC5,
where the duration (T) is a time duration required for
recovering a pressure in the first counter room 210 to a
15 normal level before applying the counter air. Thereby,
it is possible to perform a rapid pressure increase due
to the counter air supply and a rapid pressure decrease
after that in the first counter room 210. Therefore, it
is possible to remove the fine particles from the filter
20 main body 20 and transport the removed fine particle to
the second counter room 212 referred below as (B)
effectively by the counter air.
After finishing the regenerating process of the
first filter 2, a regenerating process of the second
25 filter 4 is performed continuously. As is the same as
the filter 2, the exhaust gas discharge valve 82 and the
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exhaust gas supply valve 72 are changed to a close state
, and just after this change the particle discharge
valve 52 is changed to an open state. This state is
maintained for e.g. 1 second. After e.g. 0.7 second
05 from the particle discharge vale 51 being changed to the
open state, the counter air discharge valve 305 is
opened for e.g. 0.1 second. Thereby, the regenerating
processes of the first filter 2 and the second filter 4
are finished. After that, the first filter 2 and the
second filter 4 perform a fine particle trapping
operation of the exhaust gas.
(B) Transporting process
In the transporting process, the fine particles
removed by the counter air are transported to the
15 process container 61. In this embodiment, the removed
fine particles are transported to the second counter
room 212 by a pressure of the counter air, but after
that the removed fine particles are transported to the
process container 61 through the transport pipe 5 by
20 their gravity not by the counter air. Therefore, it is
possible to transport the fine particles by a small
amount of the counter air which is not affected to a
performance of a valve of e.g. the exhaust brake.
(C) Processing process
The fine particles transported to the process
container 61 in the process portion 6 are fired on the
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plate 62 arranged at a bottom of the process container
61 by using the electric heater 50 and discharged.
Thereby, the counter air processing process of the fine
particles are finished.
05 In the first embodiment mentioned above, the
exhaust gas discharge valves 81 and 82 are arranged
respectively, but it is possible to use the valve of the
exhaust brake as the exhaust gas discharge valves 81,82.
That is to say, in the vehicles such as bus, track, and
o so on, in which the diesel engine is assembled, a valve
fo~ closing an opening area in an exhaust gas passage is
arranged so as to decrease a revolution speed of the
diesel engine. The valve mentioned above is used as the
exhaust gas discharge valves arranged in the exhaust gas
15 discharge pipe. In this case, it is possible to
decrease the number of the valves to be used .
(Second embodiment)
A second embodiment of the present invention is
shown in Figs. 12 and 13. In the first embodiment
20 mentioned above, the counter air processing process is
performed alternately and periodically to the first
filter 2 and the second filter 4. ~owever, in the
second embodiment, the counter air processing process is
performed when a pressure difference of the filter main
25 body at between the inlet portion and the outlet portion
becomes more than a predetermined value.
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If the exhaust gas from the diesel engine is
passed through a filter 400, a pressure difference Po is
generated at between an inlet portion 402 and an outlet
portion 403 of a filter main body 401, since the filter
05 main body 401 has a resistivity for transmitting the
exhaust gas. In this case, if the counter air processing
process is continued, a pressure at the inlet portion
402 is increased corresponding to an amount of the fine
particles piled up in the filter main body 401. There-
o fore, a pressure difference Pl at between the inletportion 402 and the outlet portion 403 i3 detected, and
the counter air processing process is performed when the
detected pressure difference Pl is beyond a predetermined
pressure difference P2. After the counter air processing
15 process is finished, the pressure difference P1 is
gradually decreased to a level equal to the initial
pressure difference P0 ideally or less. In this case,
the pressure difference P2 is determined by an amount of
the fine particles to be trapped and a trapping
20 performance of the filter main body, and it is less than
3 kPa preferably less than 2 kPa.
Since the fine particles trapped by the filter
main body is light and gathered, it is effective to
perform the counter air processing process when the fine
25 particles are piled up to some extent. However, if the
fine particles are piled up in excess, a pressure loss
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of the filter main body is larger and thus an effect of
the counter air processing process is decreased.
Therefore, it is necessary to perform the counter air
processing process when the pressure difference i.e.
05 pressure loss is more than a predetermined value.
In the second embodiment according to the invention,
since the counter air processing process is controlled
by the pressure difference Pl at between the inlet
portion 402 and the outlet portion 403 of the filter
main body 401, it is possible to perform the counter air
processing process effectively at a minimizing frequency~
(Third embodiment)
A third embodiment of the present invention is
shown in figs. 14 to 16. In the third embodiment, a
S partition is arranged instead of the particle discharge
valve arranged at a position in the transport pipe near
the transport inlet.
A partition 502 inclined toward the process
portion 6 from the second counter room 212 is arranged
20 along a peripheral portion 501a of a transport inlet
501. The partition 502 has an opening 502a at its
center portion. The fine particles removed from the
filter main body 20 and transported to the second
counter room 212 are fallen down in the process
25 container 61 by their gravity through the opening 502a.
Since the partition 502 is inclined toward the process
21~515q
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container 61, the fine particles fallen down in the
process container 61 are not returned to the second
counter room 212.
In the third embodiment according to the
05 invention, since it is not necessary to use the particle
discharge valve arranged near the transport inlet of the
transport pipe, it is possible to reduce the number of
the parts to be used. Moreover, since the number of the
valves is reduced, a noise due to an operation of the
o valve can be deduced.
In the present invention, a position of the
partition is not limited to the position near the inlet
portion, but it is arranged at any inner wall of the
transport pipe between the second counter room and the
15 process container.
In order to completely prevent a return of the
fine particles into the second counter room 212, it is
possible to use the particle discharge valve arranged
near the inlet of the transport pipe together with the
20 partition mentioned above.
(Fourth embodiment)
A fourth embodiment of the present invention is
shown in Figs. 17 to 19. In the fourth embodiment, the
process portion is arranged under the filter at a
25 position remote from the second counter room so as not to
return the fine particles into the second counter room.
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The process portion 6 is arranged under the
filter 2 through a transport pipe 510. That is to say,
the process portion 6 is arranged at a position remote
from an inlet 511 formed to the second counter room 212
05 toward an exhaust gas flowing direction. A length of
the transport pipe 510 is set to a length in which the
fine particles are not returned to the second counter
room 212 even if the particle discharge valve or the
partition is not used.
In the fourth embodiment, since it is not
necessary to use the particle discharge valve and the
partition, the number of the parts to be used can be
reduced. Moreover, since the number of the valves to be
operated can be reduced, it is possible to reduce an
amount of air supplied to actuators for operating the
valves.
In the first to fourth embodiments of the
invention, use is made of two filters, but it is
possible to use three or more filters.
Moreover, as shown in Fig. 11, it is possible to
use one filter by forming a by-pass pipe in the filter.
In this case, during the counter air processing, since
the exhaust gas is flowed in the by-pass pipe, the fine
particles in the exhaust gas is not trapped by the
25 filter. However, the counter air processing requires
generally a short time, and thus it is no problem in an
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actual use. Further, if the counter air processing is
not performed during a drive on an ascending road in
which a large amount of the fine particles are generated
but performed during a engine drive mode i.e. a drive on
os a highway in which a generation of the fine particles is
small, it is possible to reduce an amount of the fine
particles not trapped by the filter and discharged
through the by-pass pipe during the counter air
processing. Furthermore, if an oxidizing catalyst is
o arranged in the by-pass pipe and the fine particles are
fired in the oxidizing catalyst, it is possible to
reduce an amount of the fine particles discharged from
the by-pass pipe.
As mentioned above, according to the invention,
15 since the counter air is uniformly and rapidly introduced
to respective portions in the filter main body, it is
possible to remove the fine particles trapped in the
filter main body effectively by a simple apparatus.
Moreover, since the removed fine particles are
20 transported to the process portion and fired, it is
possible to regenerate the filter.
In the apparatus according to the invention,
since the exhaust gas supply valve is arranged in the
exhaust gas supply pipe, the fine particles are not
25 returned to the exhaust gas supply pipe if the exhaust
gas supply valve is closed. In this case, the fine
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particles are not introduced into the filter through the
exhaust gas supply pipe.
In the method and the apparatus according to the
invention, if the filter is made of a honeycomb
05 structural body having a plurality of through holes
arranged parallel which are defined by porous partitions
having a filter function, and exhaust inlets and exhaust
outlets of the through holes are sealed alternately~ it
is possible to perform the fine particle trapping
o operation and the fine particle removing operation
e.fectively.
In the method according to the invention, if the
filter main body is arranged in such a manner that a
passage direction of the through hole of the filter is
15 horizontal or inclined to a horizontal line, a vehicle
assembling performance can be improved.
In the method according to the invention, if the
counter air discharge valve is opened when a pressure
difference at between an inlet portion and an outlet
20 portion of the filter main body is more than a predeter-
mined value, the filter regeneration by the counter air
can be performed at a proper interval. Therefore, the
fine particles can be removed effectively, and an amount
of the counter air can be minimized.
In the method according to the invention, if a
relation between a valve opening duration (t) of the
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counter air discharge valves and a duration (T) is set
to T/t<5, where the duration (T) is a time duration
required for recovering a pressure in the first counter
room to a normal level before applying the counter air,
05 a pressure in the first counter room is increased by the
counter air, and then the pressure is decreased
effectively. Therefore, the fine particle removing and
transporting operations can be performed effectively by
a small amount of the counter air.
o In the method according to the invention, if one
end of the counter air supply pipe is projected in the
first counter room preferably in a tapered shape, a
pressure loss when the counter air is introduced into
the first counter room can be reduced.
In the apparatus according to the invention, if
the exhaust gas discharge valve arranged in the exhaust
gas pipe is used as a valve for an exhaust brake, the
number of the valves to be used can be reduced.
In the apparatus according to the invention, if
20 a particle discharge valve or a partition is arranged in
the transport pipe, or if the process portion is
arranged under the filter and at a position remote from
the second counter room in an exhaust gas flowing
direction,or if a connection portion between the
25 transport pipe and the second counter room is arranged
at a position lower than the exhaust gas supply pipe,
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the fine particles are not returned to the filter main
body by the exhaust gas.
In the apparatus according to the invention, if
a peripheral portion of at least an exhaust gas inlet
05 end of the filter main body is sealed airtightly in such
a manner that the filter main body is compressed in a
through hole direction, the filter main body is not
moved gradually if a vibration due to the engine or a
vibration during a movement of the vehicle is applied
thereto, and thus it is possible to prevent a crack
generation and a breakage of the filter main body.
Moreover, it is possible to prevent an exhaust gas flow
without passing through the filter main body. Further,
it is possible to decrease a support pressure of the
15 filter main body, and thus it is possible to prevent a
breakage of the filter main body.
In the apparatus according to the invention, if
the fine particles are fired by the firing means such as
electric heater, sheath heater, glow plug, and burner,
20 or by using the oxidizing catalyst or the microwave
generator together with the firing means, it is possible
to fire the fine particles effectively and rapidly.
